1. Field of the Invention
The invention is in the field of high frequency attenuator elements.
2. Description of the Prior Art
In the past attenuator elements for high frequency applications have generally been of a distributed resistance type in order to obtain better frequency response than is possible with discrete resistance elements. Discrete resistance elements if used, are grouped in a pi or tee configuration to obtain the input and output characteristic impedance value desired, such as 50 or 75 ohms.
In the distributed resistance attenuator elements, one or more distributed resistance regions are coupled among input, output and common, and the bulk of the power dissipated in the attenuator element is dissipated in the first several thousandths of an inch of the distributed resistance portion adjacent the input. The power absorption in a distributed resistance element is a decreasing exponential curve from the input conductive pad side of the resistive element toward the output.
Since the power dissipation in the distributed resistance region is concentrated at the contact area with the input conductive pad, the power dissipation capability of the attenuator element is limited. Further, the overall size of the distributed resistance region is dictated by the particular characteristic impedance desired, often leading to rather small distributed resistance regions with difficult tolerances to maintain in order to arrive at the desired characteristic impedance.